In the field of disinfection and sanitisation, there is a general move away from chemical agents, due to concerns regarding the safety and effects of these chemical compounds, or their residues, on the environment. This has led to increased interest in the use of natural compounds as disinfectants in many sectors.
The anti-microbial nature of essential oils is well documented. For example, EP 1146111 discloses a hard surface disinfecting formulation based on cinnamon oil or its actives. The compositions are tested according to European Standard EN1276, which measures anti-microbial performance on a single occasion, and over a contact time of 5 minutes. In addition, as the application is for hard surface disinfection, the anti-microbial activity is by direct contact of the active molecules with the microbes. The use of a wipe is discussed, but no details of other carriers, or the effects of different chemistries of the wipe on anti-microbial performance are given.
WO 96/39826 describes the use of essential oil components such as cinnamic aldehyde and coniferyl aldehyde to disinfect contaminated environments, although no useful performance data for the formulations is provided in the specification.
A number of patent publications have also proposed essential oils and essential oil components as a replacement for the fumigant methyl bromide, for the control of plant pathogens. WO200021364 examines the activity of essential oils from plants native to Turkey, such as Thymbra spicata, and although the primary targets are insects and fungi, some anti-bacterial activity is claimed, and methods for small scale, short term assessment of vapour activity of the oils are also described. Of the 70 essential oil components listed in the patent publication, the compound anethole was selected for further studies as a fumigant. In addition, no attempts to control the activity over a time period are described.
Feminine hygiene waste, such as used sanitary towels and tampons, and soiled nappies and incontinence pads, are often disposed of in specialist bins, and several companies offer a service relating to these bins. Typically, the bins remain in service at the customers premises for between 2 and 8 weeks. This represents a particular challenge to a disinfectant or sanitizing system, as waste contaminated with potentially pathogenic organisms is constantly being placed into the bins over a long period, steadily increasing the organic matter loading and constantly adding new pathogenic bacteria, requiring disinfection. Thus, feminine hygiene waste bins provide both an application for the technology, and an ideal demonstration of the advantages and features of the invention.
There is concern about the proliferation of microbes within the bin, and it is felt that this may present a hazard to the customers and operatives of the service companies, and may also lead to the development of unpleasant odours. To combat this, a biocidal system is often used in the bin. Traditionally, this has involved use of a large volume of liquid disinfectant, but this leads to an increased weight of material requiring disposal, and there are also concerns regarding the long-term effectiveness of a liquid system throughout the bin once the material has been absorbed into the sanitary waste at the base. Other systems are based on gas-generating systems which produce, for example, sulphur dioxide which can then penetrate and disinfect waste throughout the bin. There is some doubt about the control of release of the gas, as well as health and safety concerns about sulphur dioxide, which has lead to this technology being banned in a number of countries.
As mentioned above, in the field of disinfection, there is a general move away from chemical agents. Simple low volume disinfectant systems for use in bins, based on essential oils and plant extracts is the subject of EP 0 965 541.
The bacteria used to test the performance of the vapour based products disclosed in EP 0 965 541 were Gram-negative bacteria such as Salmonella, Pseudomonas and Escherichia coli. Gram-positive bacteria seem generally more resistant to natural plant extracts and essential oils. However, many Gram-positive bacteria are pathogenic. Staphylococcus aureus for example, can cause a number of common skin infections, and if ingested, can also cause food poisoning. In addition, the experiments reported in EP 0 965 541 did not reflect the time interval of a bin service, and in particular, did not involve repeated experiments in the same receptacle over an extended time. A truly effective natural product for use in a feminine hygiene waste bin will need to be active against all types of bacteria, and over a time frame which accurately represents the service life of the bin, both to fulfill the role of consumer and operator protection, and to achieve regulatory approval in certain markets. Thus, improving the performance of a product against Gram-positive bacteria and controlling the activity of the product to match the service interval of the bin are major features of the present invention.